Charles Darwin - Anniversaries

In 1836, a young Charles Darwin visited Australia during his voyage with HMS Beagle. He wrote that the marsupial rat-kangaroo and platypus seemed so unusual that it was almost as though two distinct Creators had been at work. Over twenty years later on 1 July 1858 Darwin and Alfred Russel Wallace jointly presented theories of evolution that rocked science and society. The subsequent publication of Darwin's book, Origin of the Species by Means of Natural Selection, on 24 November 1859 sparked an intellectual and social revolution. It transformed our understanding of life on this planet—the origins of life, our relationship to other species and the way life can adapt or fail to do so in the face of environmental change.

Expedition aboard HMS Beagle

The idea of change through evolution was not new in the nineteenth century and scientific thought was ripe for advancement in this area in 1831, when an obscure 22 year old English naturalist joined a expedition aboard HMS Beagle. Charles Darwin spent the next 5 years on a voyage of 64,000 kilometres as the Beagle charted the South American coastline then sailed on to Australia, Tahiti and the Galapagos Islands.

Throughout the journey Darwin collected many specimens and studied a diverse range of animal and plant species. He also investigated many new rock formations. By the time he reached the Galapagos Islands he became aware that similar and therefore closely related species frequently occur in adjacent regions. He discovered many odd species, similar to those on the mainland of South America although they were highly variable and suited to the island environment.

Collections and Observations

During the long journey, Darwin observed and collected 13 species of finch. Back in England, he showed these bird specimens to John Gould, a renowned wildlife illustrator. Gould’s detailed observations and accurate illustrations showed that the birds were distinguishable by the size and shape of their beaks. They were, in fact, all closely related species with adaptations of the beak perfectly suited to its food source. Why so much variation in such a small area? Darwin believed that the finches were evidence for evolution. He proposed that the different finch species were descendants of a common ancestor. Over time the birds had evolved very different feeding habits to exploit the range of food sources on each island. He believed that enough variation must have existed within the original finch population to enable the selection of different beak sizes and shapes.

By 1856 Darwin had returned from his voyage, with observations and data from studying variation within species and the similarities between fossils and living species. He had come to see evolution as a continuous process—sure that evolution came about, and new species evolved from older ones, through a process that he called Natural Selection. However, Darwin was initially reluctant to publish his findings as he was unable to explain the mechanism by which inherited traits allowed natural selection to occur.

Darwin and Wallace

During the 1850s Alfred Russel Wallace travelled to South America and South-East Asia in search of the exotic. He funded his adventures by collecting rare and unusual wildlife for museums and private collections. From detailed observations of wildlife he developed similar ideas to Darwin for describing the process of evolution. Sharing these observations led Alfred Wallace and Charles Darwin to jointly present their theories at a meeting of the Royal Society in London 1858. Both men supported a view that the variation of individuals and the degree to which they are adapted to their environment determine their chance of surviving and reproducing. This new theory of evolution and natural selection provided an explanation of how species changed over time and new species arose.

Darwin's Book

Darwin was primarily credited with formulating the theory of evolution by natural selection as a result of the subsequent publication of his The Origin of Species by Means of Natural Selection. The Theory of Evolution and Natural Selection remained controversial for many years following the publication of Darwin’s book, as it conflicted with theological beliefs of the time. Even today some reject the theory as lacking in conclusive geological or fossil evidence. However, world-wide The Origin of Species by Means of Natural Selection is regarded as one of the most important books ever written. It changed the way that we regard ourselves in the living world and also provides the foundation of modern biology.